Agronomic and environmental performance of dairy farms in a warmer, wetter climate

Abstract

The northeast United States has experienced higher temperatures, more annual precipitation, and more frequent heavy rain events in recent decades. These trends appear likely to continue, and they may depress crop yields and exacerbate environmental problems associated with the region’s dairy farms. To investigate these possibilities, we used the Agricultural Policy/Environmental eXtender (APEX) model to simulate runoff, erosion, nutrient losses, and crop yields on two Vermont farms in a small set of possible future climates. Raising temperatures by 2°C, combined with increasing total precipitation or changing the seasonality of precipitation, had relatively modest effects on any outcome (less than 10% change in median values). However, a combination of higher temperatures and more intense precipitation led to increased runoff volumes and larger soil and nutrient losses. Median values of runoff, sediment, and nutrient losses increased by 2% to 15% at one site and by 36% to 58% at the other (although the changes at the latter site were relative to very low baseline values), while the 95th percentile rose by 6% to 19% and 53% to 65%. This suggests that management practices adapted to reducing runoff etc. in extreme precipitation events will be increasingly valuable in the coming years. Corn (Zea mays L.) silage yields changed by less than 10% in all simulations, and in some cases increased slightly. However, modeling that includes many additional factors that can reduce yields (such as new pests, or delays to farm operations in wet conditions) is needed for a more complete understanding of how climate change may affect the viability of forage production on dairy farms in this region.